Lecture 19: Stress · What stresses you? exams, grades. deadlines. traffic. family relationships....

STRESS

John Gabrieli9.00

STRESSWhat stresses you?


exams, gradesdeadlinestrafficfamily relationshipslife after college, etc., etc.



What does not stress you?



What does not stress you?being eaten or eating another being

STRESSWhat stresses a zebra?

(Robert Saplosky, Why Zebras Don’t Get Ulcers)

STRESSWhat stresses a zebra?

serious physical injury predators (lions)starvation

STRESS• psychological and physiological response to a stimulus (stressor) that alters the body’s equilibrium

STRESSAcute Chronic

Physical injury hunger, cancer

Psychological deadline chronic work pressure

Social humiliation chronic isolation

STRESS• for animals, stress is often acute, physical, responsive• for people in industrial society, stress is often chronic, psychosocial, anticipatory

Neurobiological Substrates of Dread

• Berns 2006, Science• fMRI and waiting for a cutaneous electrical

shock to foot• each trial starts with information about voltage

level and amount of time• at first 100% of trials had voltage• choice phase, e.g., 90% voltage in 3 secs or

60% voltage in 27 secs• some people prefer more voltage now than to

wait for shock (extreme dreaders)

More Voltage (Pain) Associated with Greater Brain Activation

Source: Berns, G. S., et al. "Neurobiological Substrates of Dread." Science, 312, no.5774 (2006): 754-58. © AAAS. All rights reserved. This content is excluded from ourCreative Commons license. For more information, see http://ocw.mit.edu/fairuse.

http://ocw.mit.edu/fairuse

Extreme Dreaders Had Earlier & More Sustained ActivationBetween Cue and Shock

Source: Berns, G. S., et al. "Neurobiological Substrates of Dread." Science, 312, no.5774 (2006): 754-58. © AAAS. All rights reserved. This content is excluded from ourCreative Commons license. For more information, see http://ocw.mit.edu/fairuse.


Mortality• 1900 ?

Mortality• 1900 - infectious diseases & childbirth

pneumoniatuberculosisinfluenza (1918 - more than WWI)childbirth (young women)

• 2007?

Mortality• 1900

pneumoniatuberculosisinfluenza (1918 - more than WWI)childbirth (young women)

• 2007 - cumulative damageheart diseasecancercerebrovascular disorders

STRESS• Hans Selye - 1930s - insightful scientists, not so good at handling rats

Colleague extracted ovarian chemical - what does it do? - Selye injected rats daily -dropped them, ran around - several months later - peptic ulcers, enlarged adrenal glands, shrunken immune tissue - also in control rats- exposed rats to many stressors, all had the same result

STRESS•The Stress Response is similar to a broad array of stressors

• if stressors go on for too long, they make you sick

STRESS & AUTONOMIC NERVOUS SYSTEM

• Sympathetic nervous system• brain to spine, organs, blood vessels, sweat glands, muscles and hairs (goosebumps)• emergency, arousal, activation• four Fs - flight, fright, fight, and sex• releases epinephrine/norepinephrine

(adrenaline/noradrenaline)•Parasympathetic nervous system

sleep, eating, relaxation

STRESS & AUTONOMIC NERVOUS SYSTEM

Sympathetic ParasympatheticHeart speeds up slows downBlood to muscles from muscles

STRESS & HORMONES

• hypothalamusreleases CRH (corticotropin releasing hormone) to anterior pituitary

• anterior pituitary (15 sec)releases adrenocorticotropic hormone(ACTH) into blood

• adrenal glands (kidney) (few minutes)release glucocorticoids (steroids) (cortisol)

Adaptive Stress-Response Stress-Related Disorder

The Stress Responseand its Consequences

• Mobilization of energy

• Increased cardiovascular tone

• Suppression of digestion

• Suppression of growth

• Suppression of reproduction

• Suppression of immune system

• Sharpening of cognition

• Myopathy, fatigue, diabetes

• Stress-induced hypertension

• Ulceration, colitis

• Psychogenic dwarfism

• Amenorrhea, impotency, loss of libido

• Increased disease risk

• Neuron death



• Increased cardiovascular tone • Stress-induced hypertension• Ventricular hypertrophy

– (top predictor of cardiac arrest controlling for age)

• Damage to arteries– Plaque formation– Damaged inflamed blood vessels

• Increase heart rate• Increase blood pressure to muscle (and brain) away from digestive system • Decrease kidney function to keep water• Void the bladder

This image is in the public domain.



• Suppression of digestion • Ulceration, colitis

• Ulcer – hole in the wall of an organ

• Peptic (gastric, esophageal,duodenal)

– Robert Warren/Barry Marshall/2005 Nobel

• – 1983– Bacterium – heliobacter

pylori swallowed/gastritis– Antibiotic treatment– But 15% of cases unrelated – And only 10% with

bacterium get ulcers

Adaptive Stress-Response Stress-related Disorder


• Suppression of growth • Psychogenic dwarfism

• British Victorian family• favorite son killed at 13• Bereaved mother takes to bed

– ignores 6 year-old son• “David is that you? Oh, it is only

you.”• David was perfect• 5ft as an adult• J.M. Barrie writes Peter Pan

© Macmillan. All rights reserved. This content is excluded from our Creative Commons license. For more information,see http://ocw.mit.edu/fairuse. Source: Sapolsky, R. Why Zebras Don't Get Ulcers. Macmillan, 2004. .


mid 1950sMeyer FriedmanRay Rosenmancardiologypractice

4/5 years later

TYPE APERSONALITY

STRESSType-A Personality

Friedman & Rosenman, 1960simmensely competitive, over-achieving,time-pressured, impatient, hostileincreased risk of cardiovascular diseaselike smoking, or high cholesterol

STRESSType-A Personality

failures to replicateapplies to early age key - hostility - many replicationssuppressed expression

Adaptive Stress-Response Stress-related Disorder

(Sapolsky, 1992)


• Mobilization of energy

• Increased cardiovascular tone

• Suppression of digestion

• Suppression of growth

• Suppression of reproduction

• Suppression of immune system

• Sharpening of cognition

• Myopathy, fatigue, diabetes

• Stress-induced hypertension

• Ulceration, colitis

• Psychogenic dwarfism

• Amenorrhea, impotency, loss of libido

• Increased disease risk

• Neuron death

© Macmillan. All rights reserved. This content is excluded from our Creative Commons license. For more information,see http://ocw.mit.edu/fairuse. Source: Sapolsky, R. Why Zebras Don't Get Ulcers. Macmillan, 2004.


POST-TRAUMATIC STRESS DISORDER (PTSD)

• a severe anxiety disorder that can develop after exposure to any event which results in psychological trauma• re-experience original trauma through flashbacks and dreams, increased arousal, hypervigilance• assault/rape, combat• sustained in about 20% of people


• smaller hippocampal volumes in PTSD (some variability in results)



• cause or consequence?



• cause or consequence?

• twin study - correlation among monozygotic twins with and without combat exposure in hippocampalvolume

Association between greater PTSD severity in combat-exposed twin and smaller hippocampal volumein both combat-exposed and non-combat exposed twin

Reprinted by permission from Macmillan Publishers Ltd: Nature Neuroscience. Source:Gilbertson, M. W., et al. "Smaller Hippocampal Volume Predicts Pathologic Vulnerabilityto Psychological Trauma." Nature Neuroscience 5, no. 11 (2002): 1242-47. © 2002.


• prospective study• Israeli military, 50 recruits before and after military service and stressful events• increase in stress associated with greater amygdala and hippocampus response to stress-relate content• amygdala reactivity before stress predicted increase in stress symptoms• hippocampus change over time correlated with stress symptoms; content-specific

(A) Timeline (months) of the prospective imaging study.

Admon R et al. PNAS 2009;106:14120-14125

©2009 by National Academy of Sciences

Courtesy of Talma Hendler. Used with permission.

(Weiss, Levine, Sehgman)

Psychological Modifiersof the Stress Response

• Outlets for frustration• Sense of predictability and of control• A perception of life improving• Social support


• Outlets for frustration (Jay Weiss)rats receive mild shocksprolonged stress response - heart rate up,

glucocorticoid secretion up, ulcersother rats can gnaw on wooden bar, or eat, or drink, or run on wheel - fewer ulcersor run to another rate and bite itbaboons attack bystanders after losing a fight


•Sense of predictability and of control• rats hear warning bell before shock - fewer ulcers -

predictability (vs. unknown)• food delivered to rat at intermittent intervals vs.

random delivery of equal food - glucocorticoid levels go up

• rat given lever to avoid shocks - even if lever is disconnected to shocks, stress response is reduced

• people - noxious noises – one person has button to press to stop noise - less hypertensive whether button is pressed or not

• occupational stress - high demand & low control


• Sense of predictability and of controlRodin & Langer, 1977• nursing home

group A – make decisions for yourselfwhere to receive visitorswhen to watch moviewhat houseplant to take care of

group B – no instructions to make decisionsgot plant, but staff took care of plant

1.5 years later – group A more cheerful, active, and alert, healthier, half as many had died


• Sense of predictability and of controlCultural Influences

Individualist – US/EuropeCollectivist – East Asian (and rest of the world?)

Elementary school 7-9 year olds, Asian-American or Anglo-American – Ms. Smith – six markers (6 colors) –six piles of anagrams (family, animal, etc. RIBD)

Random assignment to 3 groups- you choose, teacher chooses, mother chooses- Anglo-Americans self = 4X Ms Smith, 2.5X mother- Asian-Americans - 30% more for mother than self, 2X than Ms Smith


• Sense of predictability and of control

life and death struggle

Richter, 1957Water temperature and enduranceRats in a jar – how long does rat swim before drowning?15 minutes-60 hours before giving up, much variation

Picked up rats, let them wriggle free, in and out of water,

Average of 60 hours of effort


• Social support• Primates - after stress response, among strangers -

worse; among friends - better (measured by glucocorticoids)

• People - stressor (public speaking, math task, argument with strangers) - less cardio-vascular response with a supportive friend present

• Observations - people with spouses/close friends live longer; when spouse dies, risk of dying increases; parents of children killed in war have higher risk of disease/mortality only if divorced/widowed; patients with severe coronary disease had 3x death rate over 5 years if lacking social support

(Weiss, Levine, Sehgman)


• A perception of life improving (worsening)• rats/shocks - rat #1 - 10/hr; rat #2 - 50/hr;Day 2 - all rats get 25/hr; 10-25 becomes

hypertensive

Shock alone

+ another rat

50 25 shocks

+ warning signal

+ wood bar

+ lever

+ friends

Risk of Ulcer

Embodied Cognition

• the nature of the human mind largely determined by the form of the human body• ideas, thoughts, concepts, categories shaped by aspects of the body• is emotional pain (social, romantic rejection) built out of physical pain?

Painsensory - objectiveaffective - subjective (suffering, unpleasantness)

Pain Processing

cingulatesomatosensory cortext

© source: unknown. All rights reserved. This content is excluded from our CreativeCommons license. For more information, see http://ocw.mit.edu/fairuse.


Hypnotic Suggestion of High or Low Pain

Source: Rainville, P., et al. "Pain Affect Encoded in Human Anterior Cingulate but not SomatosensoryCortex." Science 277, no. 5328 (1997): 968-71. © AAAS. All rights reserved. This content is excludedfrom our Creative Commons license. For more information, see http://ocw.mit.edu/fairuse.


Methodology and results from an fMRI study of social exclusion. (a)Example of what participants viewed while in the scanner. Participants were included in the ball-tossing game during one round and excluded during another. (b)Participants showed increased dorsal anterior cingulate cortex (dACC) activity during the exclusion compared with the inclusion episode. (c) Participants' levels of self-reported distress correlated highly with dACC activity during the exclusion episode compared with the inclusion episode.

Social Pain

Source: Eisenberger, N. I., and M. D. Lieberman. "Why Rejection Hurts: A Common NeuralAlarm System for Physical and Social Pain." Trends in Cognitive Sciences 8, no. 7 (2004):294-300. Courtesy of Elsevier, Inc., http://www.sciencedirect.com. Used with permission.

http://www.sciencedirect.com

Romantic Pain• Physical pain (heat)• Romantic pain/social rejection• Participants “felt intensely rejected as a

result of recently experiencing an unwanted romantic relationship break-up”

• Viewed pictures of ex-partners and thought about being rejected (vs. viewing pictures of friends and thinking about positive experiences

Neural overlap between social rejection & physical pain

Kross E et al. PNAS 2011;108:6270-6275

Copyright (2011) National Academy of Sciences, U.S.A. Used with permission.

Pain of Social Rejection

• random assignment- 2000 mg acetaminophen (Tylenol, Excedrin) for 3 weeks- placebo

- provide daily reports- by Day 15, less painful resposne to

rejection- less brain response to social rejection

60

threat that others' judgments or one's own actions will confirm negative stereotypes about one's group

stress from stereotype knowledge undermines performance

Stereotype Threat

Source: Steele, Claude M. "A Threat in the Air: How StereotypesShape Intellectual Identity and Performance." AmericanPsychologist 52, no. 6 (1997): 613-29.Courtesy of AmericanPsychological Association. Used with permission.

• faster for “unpleasant or black”than “unpleasant or white”?

IMPLICIT ASSOCIATION TEST IAT• faster for white + pleasant than black + pleasant? 75% of whites; 50% of blacks

• automatic sterotypes? attitudes vs.associations?

• many domains - aging, techies vs. fuzzies/in-group vs. outgroup

•https://implicit.harvard.edu/implicit/

https://implicit.harvard.edu/implicit/

IMPACT OF INTERRACIAL CONTACT ON EXECUTIVE FUNCTION

• Richeson et al., 2003• White individuals completed IAT• Go to a different room, interact with either black

or white experimenter, videotaped comments on college fraternity system and racial profiling after 9/11

• Go back and perform Stroop task• Measure interference (incompatible (BLUE)

minus control (BLUE) trials))

Source: Richeson, J., and J. Shelton. "When Prejudice Does Not Pay: Effects of Interracial Contact on ExecutiveFunction." Psychological Science 14, no. 3 (2003): 287-90. © Sage publications. All rights reserved. Thiscontent is excluded from our Creative Commons license. For more information, see http://ocw.mit.edu/fairuse.


The YerkesThe Yerkes--Dodson LawDodson Law

Image is Figure 3 from Diamond D. M., et al. "The Temporal Dynamics Model of Emotional Memory Processing:A Synthesis on the Neurobiological Basis of Stress-Induced Amnesia, Flashbulb and Traumatic Memories,and the Yerkes-Dodson Law." Neural Plasticity 33 (2007) dx.doi.org/10.1155/2007/60803.

dx.doi.org/10.1155/2007/60803

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9.00SC Introduction to PsychologyFall 2011

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Lecture 19: Stress · What stresses you? exams, grades. deadlines. traffic. family relationships....

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